Thermal management assembly for an electrified vehicle

ABSTRACT

A cover for a housing of an electric machine is provided. The cover may include an inner sidewall and an outer sidewall. The outer sidewall may be spaced apart from the inner sidewall to define a coolant channel therebetween. The inner sidewall and outer sidewall may be defined by an interior surface of the cover such that the coolant channel receives end windings of a stator of the electric machine when the cover is secured to the housing. The interior surface of the cover may define features between the sidewalls to promote turbulence of coolant flowing through the coolant channel. The interior surface of the cover may define a meandering trough between the sidewalls to form a predetermined coolant path relative to a location of the end windings when the cover is secured to the housing.

TECHNICAL FIELD

The present disclosure relates to a thermal management assembly for anelectric machine of an electrified vehicle.

BACKGROUND

Extended drive range technology for electrified vehicles, such asbattery electric vehicles (“BEVs”) and plug in hybrid vehicles(“PHEVs”), is continuously improving. Achieving these increased ranges,however, often requires traction batteries and electric machines to havehigher power outputs and associated thermal management systems withincreased capacities in comparison to previous BEVs and PHEVs.

SUMMARY

A cover for a housing of an electric machine includes an inner sidewalland an outer sidewall. The outer sidewall is spaced apart from the innersidewall to define a coolant channel therebetween. The inner sidewalland outer sidewall are defined by an interior surface of the cover suchthat the coolant channel receives end windings of a stator of theelectric machine when the cover is secured to the housing. The interiorsurface of the cover may define features between the sidewalls topromote turbulence of coolant flowing through the coolant channel. Thefeatures may be one of a plurality of individual extrusions scatteredabout the coolant channel, concentric circular extrusions about a hub ofthe coolant channel, or post extrusions spaced apart from one anotheralong the inner sidewall or outer sidewall. The interior surface of thecover may define a meandering trough between the sidewalls to form apredetermined coolant path relative to a location of the end windingswhen the cover is secured to the housing. The cover may define an inletand an outlet open to the coolant channel. The stator and the outersidewall may be sized such that the coolant channel is sealed when thecover is secured to the housing. The cover may further define one ormore fins on an exterior surface proximate the coolant channel tooperate as a heat sink therefore.

A housing of an electrified vehicle electric machine includes a cover,an inner sidewall, and an outer sidewall. The cover defines an interiorsurface and an exterior surface. The inner sidewall is defined by theinterior surface and has a circular shape. The outer sidewall is definedby the interior surface and spaced apart from the inner sidewall todefine a coolant channel therebetween. The interior surface is arrangedwith the housing such that the coolant channel receives end windings ofa stator of the electric machine when the cover is secured to thehousing. The interior surface may further define a meandering troughbetween the inner sidewall and outer sidewall for coolant to flowtherethrough. The outer sidewall may further define an inlet and anoutlet open to the coolant channel. The outer sidewall may be spacedfrom an edge of the cover such that a rotor of the electric machine atleast partially extends in between the inner sidewall. The innersidewall may define a cavity sized for a rotor of the electric machineto at least partially extend therethrough. The interior surface maydefine features between the sidewalls to promote turbulence of coolantflowing through the coolant channel. A sealant may be disposed betweenthe sidewalls and the stator. The stator may further define a bracketextending from a face of the stator sized to receive a key defined bythe outer sidewall to secure the outer sidewall to the stator. Thestator may define a slot sized to receive a tab defined by the outersidewall to secure the outer sidewall to the stator. An O-ring plate maybe sized for disposal between the sidewalls and the stator. One or morefins may extend from an exterior cover surface and may be locatedproximate the coolant channel. The one or more fins may be adjacent oneof an inlet or outlet defined by the outer sidewall.

A method to form an encasement about end windings of an electric machineincludes immersing the end windings in a mold material bath and thenremoving the end windings for the mold material to solidify and define abase mold upon the end windings; positioning inlet and outletplaceholders extending in and out of the base mold; immersing the basemold in an epoxy bath and then removing the base mold for the epoxy tosolidify and define an over mold; and dissolving the base mold via aliquid applied to the base mold such that a cavity is defined betweenthe end windings and the over mold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram illustrating an example of an electrifiedvehicle.

FIG. 1B is a perspective view of an example of an electric machine.

FIG. 2A is a side view, in cross-section, of a portion of an electricmachine having a closed coolant channel for end windings.

FIG. 2B is a side view, in cross-section, of a portion of an electricmachine having an open coolant channel for end windings.

FIG. 3A is a perspective view of an electric machine assembly showing ahousing with a cover partially exploded therefrom.

FIG. 3B is a side-view, in cross-section, of a portion of the electricmachine assembly of FIG. 3A.

FIG. 4A is a first perspective view of the cover of FIG. 3A.

FIG. 4B is a second perspective view of the cover of FIG. 3A.

FIG. 5 is an example of a portion of a coolant channel defining a troughfor coolant to flow therethrough.

FIG. 6 is an example of a portion of a coolant channel defining a troughfor coolant to flow therethrough.

FIG. 7 is an example of a portion of a coolant channel defining anexample of features on an interior surface to influence coolant flow.

FIG. 8 is an example of a portion of a coolant channel defining anexample of features on an interior surface to influence coolant flow.

FIG. 9 is an example of a portion of a coolant channel defining anexample of features on an interior surface to influence coolant flow.

FIG. 10A is a perspective view of a portion of an electric machine.

FIG. 10B is a perspective view of a fastener assembly of the portion ofthe electric machine of FIG. 10A.

FIG. 10C is a side view, in cross-section, of the portion of theelectric machine of FIG. 10A.

FIG. 10D is a side detail view, in cross-section, of the fastenerassembly of FIG. 10B.

FIG. 10 E is a side view of an encasement of the portion of the electricmachine of FIG. 10A.

FIG. 11A is a perspective view of a portion of an electric machine.

FIG. 11B is a perspective view of a fastener assembly of the portion ofthe electric machine of FIG. 11A.

FIG. 11C is a perspective view of the fastener assembly of the portionof the electric machine of FIG. 11A.

FIG. 12 is a schematic diagram of an example of a portion of an electricmachine.

FIG. 13 is a schematic diagram of an example of a step in a moldprocess.

FIG. 14 is a schematic diagram of an example of another step in a moldprocess.

FIG. 15 is a schematic diagram of an example of yet another step in amold process.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments may take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentdisclosure. As those of ordinary skill in the art will understand,various features illustrated and described with reference to any one ofthe figures may be combined with features illustrated in one or moreother figures to produce embodiments that are not explicitly illustratedor described. The combinations of features illustrated providerepresentative embodiments for typical applications. Variouscombinations and modifications of the features consistent with theteachings of this disclosure, however, could be desired for particularapplications or implementations.

FIG. 1A depicts a schematic of an example of a PHEV, referred to as avehicle 12 herein. The vehicle 12 may comprise one or more electricmachines 14 mechanically connected to a hybrid transmission 16. Theelectric machines 14 may be capable of operating as a motor or agenerator. In addition, the hybrid transmission 16 may be mechanicallyconnected to an engine 18. The hybrid transmission 16 may also bemechanically connected to a drive shaft 20 that is mechanicallyconnected to a set of wheels 22. The electric machines 14 can providepropulsion and deceleration capability when the engine 18 is turned onor off. The electric machines 14 may also act as generators and mayprovide fuel economy benefits by recovering energy that would normallybe lost as heat in the friction braking system. The electric machines 14may also provide reduced pollutant emissions since the hybrid-electricvehicle 12 may be operated in electric mode or hybrid mode under certainconditions to reduce overall fuel consumption of the vehicle 12.

A traction battery or battery pack 24 stores and provides energy thatmay be used by the electric machines 14. The traction battery 24 mayprovide a high voltage DC output from one or more battery cell arrays,sometimes referred to as battery cell stacks, within the tractionbattery 24. The battery cell arrays may include one or more batterycells. The traction battery 24 may be electrically connected to one ormore power electronics modules 26 through one or more contactors (notshown). The one or more contactors isolate the traction battery 24 fromother components when opened and connect the traction battery 24 toother components when closed. The power electronics module 26 may alsobe electrically connected to the electric machines 14 and provides theability to bi-directionally transfer electrical energy between thetraction battery 24 and the electric machines 14. For example, thetraction battery 24 may provide a DC voltage while the electric machines14 may require a three-phase AC voltage to function. The powerelectronics module 26 may convert the DC voltage to a three-phase ACvoltage as required by the electric machines 14. In a regenerative mode,the power electronics module 26 may convert the three-phase AC voltagefrom the electric machines 14 acting as generators to the DC voltagerequired by the traction battery 24. Portions of the description hereinare equally applicable to a pure electric vehicle. For a pure electricvehicle, the hybrid transmission 16 may be a gear box connected to anelectric machine 14 and the engine 18 may not be present.

In addition to providing energy for propulsion, the traction battery 24may provide energy for other vehicle electrical systems. A DC/DCconverter module 28 may convert high voltage DC output of the tractionbattery 24 to a low voltage DC supply that is compatible with othervehicle loads. Other high-voltage loads, such as compressors andelectric heaters, may be connected directly to the high-voltage withoutthe use of the DC/DC converter module 28. The low-voltage systems may beelectrically connected to an auxiliary battery 30 (e.g., 12V battery).

A battery electrical control module (BECM) 33 may be in communicationwith the traction battery 24. The BECM 33 may act as a controller forthe traction battery 24 and may also include an electronic monitoringsystem that manages temperature and charge state of each of the batterycells. The traction battery 24 may have a temperature sensor 31 such asa thermistor or other temperature gauge. The temperature sensor 31 maybe in communication with the BECM 33 to provide temperature dataregarding the traction battery 24. The temperature sensor 31 may also belocated on or near the battery cells within the traction battery 24. Itis also contemplated that more than one temperature sensor 31 may beused to monitor temperature of the battery cells.

The vehicle 12 may be, for example, an electrified vehicle whichincludes components for a PHEV, a FHEV, a MHEV, or a BEV. The tractionbattery 24 may be recharged by an external power source 36. The externalpower source 36 may be a connection to an electrical outlet. Theexternal power source 36 may be electrically connected to electricvehicle supply equipment (EVSE) 38. The EVSE 38 may provide circuitryand controls to regulate and manage the transfer of electrical energybetween the power source 36 and the vehicle 12. The external powersource 36 may provide DC or AC electric power to the EVSE 38. The EVSE38 may have a charge connector 40 for plugging into a charge port 34 ofthe vehicle 12. The charge port 34 may be any type of port configured totransfer power from the EVSE 38 to the vehicle 12. The charge port 34may be electrically connected to a charger or on-board power conversionmodule 32. The power conversion module 32 may condition the powersupplied from the EVSE 38 to provide the proper voltage and currentlevels to the traction battery 24. The power conversion module 32 mayinterface with the EVSE 38 to coordinate the delivery of power to thevehicle 12. The EVSE connector 40 may have pins that mate withcorresponding recesses of the charge port 34.

The various components discussed may have one or more associatedcontrollers to control and monitor the operation of the components. Thecontrollers may communicate via a serial bus (e.g., Controller AreaNetwork (CAN)) or via discrete conductors.

Current examples of thermal management assemblies for electric machinesmay introduce oil to portions of the electric machine for coolingpurposes. The oil may be dripped or sprayed onto wire end windings ofthe electric machine. However, this practice may not be very effectivein cooling the end windings due to a non-uniformity of coolant flow asapplied to the end windings. An air cooled thermal management assemblyis another example of an assembly to assist in managing thermalconditions of an electric machine. In this example, a fan or blower maybe located adjacent the end windings to push air thereto for coolingpurposes.

FIG. 1B shows an example of an electric machine for an electrifiedvehicle, referred to generally as an electric machine 100 herein. Theelectric machine may include a stator core 102 and a rotor 106.Electrified vehicles may include two electric machines. One of theelectric machines may function primarily as a motor and the other mayfunction primarily as a generator. The motor may operate to convertelectricity to mechanical power and the generator may operate to convertmechanical power to electricity. The stator core 102 may define an innersurface 108 and a cavity 110. The rotor 106 may be sized for disposaland operation within the cavity 110. A shaft (not shown) may be operablyconnected to the rotor 106 to drive rotation thereof.

Windings 120 may be disposed within the cavity 110 of the stator core102. In an electric machine motor example, current may be fed to thewindings 120 to obtain a rotation force on the rotor 106. In an electricmachine generator example, current generated in the windings 120 by arotation of the rotor 106 may be removed to power vehicle components.Portions of the windings 120, referred to as end windings 126 herein,may protrude from the cavity 110. During operation of the electricmachine 100, heat may be generated along the windings 120 and endwindings 126.

FIGS. 2A and 2B show examples of portions of a closed coolant channelassembly and an open coolant channel assembly to assist in managingthermal conditions of end windings of an electric machine. For example,FIG. 2A shows a closed coolant channel assembly 125 mounted to thestator core 102 via a set of tabs 101 sized for insertion withinapertures (not shown) of the closed coolant channel assembly 125. It iscontemplated that other suitable features may be used to mount theclosed coolant channel assembly 125 to the stator 102. The closedcoolant channel assembly 125 may define a cavity 123 sized to receiveend windings 126. An inlet 121 may deliver coolant to the cavity 123 toassist in managing thermal conditions of the end windings 126. Coolantmay exit the cavity 123 via an outlet 119. As another example, FIG. 2Bshows an open coolant channel assembly 117 which may be mounted to thestator 102. The open coolant channel assembly 117 may define a cavity115 sized to receive end windings 126. An inlet 113 may deliver coolantto the cavity 115 to assist in managing thermal conditions of the endwindings 126. Coolant may exit the cavity 115 via an outlet 111.Packaging constraints and desired performance of a coolant system mayfactor into a decision to use an open or closed coolant channelassembly.

FIG. 3A shows an example of a housing to retain vehicle components,referred to as a housing 130 herein. Examples of vehicle componentswhich may be retained within the housing 130 include an electricmachine, such as the electric machine 100, or a vehicle transmission. Acover 140 may be secured to the housing 130. FIG. 3B shows across-sectional view of a portion of FIG. 3A. The cover 140 may bearranged with a stator core 141 such that a channel 149 is defined bythe cover 140 to receive end windings 139 extending from the stator core141. For example, the channel 149 defined by the cover 140 may be sizedsuch that end windings 139 protruding from the stator core 141 may bedisposed therein. A rotor 155 may be operably connected to the statorcore 141.

FIGS. 4A and 4B show two views of the cover 140. As mentioned, the cover140 may define a coolant channel integrated therewith and oriented toalign with the end windings 126. For example, the coolant channel mayinclude an inner sidewall 143 and an outer sidewall 145 extending froman interior surface 147 of the cover 140. The inner sidewall 143 and theouter sidewall 145 may define the channel 149 therebetween and extendfrom an interior surface 147 of the cover 140. A surface or memberbetween the inner sidewall 143 and the outer sidewall 145 may bereferred to as a base sidewall. The channel 149 may be sized such thatthe end windings 139 are received therein when the cover 140 is mountedto the housing 130. The cover 140 and the stator core 141 may bearranged with one another to create a seal therebetween and such thatcoolant delivered to the channel 149 is contained therein. The innersidewall 143 and the outer sidewall 145 may be arranged with one anotherto form a tire or hub shape such that the rotor 155 may extend through acavity defined by the inner sidewall 143 without interference. Inanother example, the inner sidewall 143, base sidewall, and the outersidewall 145 may assist in defining a coolant channel and be part of aseparate component secured to the cover 140 or for securing to a statorcore, such as the stator core 141.

The cover 140 may define an inlet 146 open to the channel 149 to delivercoolant thereto and such that the end windings 139 disposed within thecavity are contacted by coolant flowing therethrough. Various suitablelocations may be available for the inlet 146. The cover 140 may definean outlet 148. Coolant may exit the channel 149 via the outlet 148.Various suitable locations may be available for the outlet 148. Thecover 140 may define one or more features on an exterior surface 151 ofthe cover 140 to assist in managing thermal conditions of the endwindings 139. For example, one or more fins 150 may be defined by thecover 140. The fins 150 may be located adjacent the inlet 146, theoutlet 148, may be dispersed about a portion of the exterior surface ofthe cover 140 corresponding to the channel 149, or may be proximate thechannel 149 to operate as a heat sink. Locating the fins 150 proximate aportion of the channel 149 in which coolant flows may assist inremoving, for example, heat from the coolant which is taken from the endwindings 139 during operation thereof. Features within the channel 149may also assist in managing thermal conditions of the end windings 139.For example, features may be defined within the channel 149 to assist inpromoting turbulence of coolant flowing therethrough. Promotion ofturbulence of coolant may draw additional heat from the end windings 139in comparison to a constant coolant flow.

FIGS. 5 through 9 show examples of features which may assist inpromoting turbulence of coolant flowing through the channel 149 or mayassist in providing a targeted flow of coolant within the channel 149.FIGS. 5 and 6 show examples in which the cover 140 defines a meanderingtrough to assist in distributing coolant to a desired area. For example,the meandering trough may correspond to a location of a portion orportions of the end windings 139 which generate more heat than otherportions of the end windings 139 during operation. In one example, themeandering trough may be a recess defining a depth below the interiorsurface 147. In another example, the meandering trough may be defined byraised edges extending from the interior surface 147 of the cover 140.

In FIG. 5, a meandering trough 160 is formed in a curve pattern in asnake-style to direct a flow of coolant therethrough. In FIG. 6, ameandering trough 164 is formed in a zig-zag pattern to direct a flowcoolant therethrough. A helical form is another example of a shape forthe meandering trough. In one example, the patterns of the meanderingtroughs 160 and 164 may provide for an extended contact of coolant withthe end windings 139 disposed within the channel 149. In this example,the meandering troughs 160 and 164 may direct a flow of coolant topredetermined and targeted areas of or around the end windings 139.While the meandering troughs 160 and 164 are shown on a first surfacebetween the inner sidewall 143 and the outer sidewall 145, it iscontemplated that the meandering troughs 160 and 164 may be located ordefined on the sidewall surfaces. Optionally, the meandering troughs 160and 164 may be defined by a separate component, such as an epoxy overmold. The over mold may be formed such that the end windings 139 extendtherethrough and into the channel 149.

FIGS. 7 through 9 show examples of features which may assist inpromoting turbulence of coolant flowing through the channel 149. FIG. 7shows post extrusions 174 defined by the outer sidewall 145. It iscontemplated that the post extrusions 174 may be separate componentssecured to the outer sidewall 145. The post extrusions 174 may also bespaced apart from one another along the inner sidewall 143. Coolantflowing within the channel 149 may contact the post extrusions 174 tochange or disrupt a flow of the coolant. FIG. 8 shows concentriccircular extrusions 180 defined by the cover 140. It is contemplatedthat the concentric circular extrusions 180 may be separate componentssecured to the cover 140. The concentric circular extrusions 180 may bespaced apart from one another along the interior surface 147 of thecover 140. It is also contemplated that the concentric circularextrusions may be spaced apart from one another on the inner sidewall143 or the outer sidewall 145. Coolant flowing within the channel 149may contact the concentric circular extrusions 180 to change or disrupta flow of the coolant. FIG. 9 shows individual extrusions 184 defined bythe interior surface 147 of the cover 140 scattered about the channel149. It is also contemplated that the individual extrusions may beseparate components secured to the cover 140. The individual extrusions184 may be spaced apart from one another along the interior surface 147of the cover 140 or along the sidewalls. Coolant flowing within thechannel 149 may contact the individual extrusions 184 to change ordisrupt a flow of the coolant.

FIGS. 10A through 10E show an example of a portion of an electricmachine, referred to generally as an electric machine 200 herein. Theelectric machine 200 may include a stator 202, end windings 204, anencasement 206, a rotor 208, and a plate 210. In this example, arelationship between the encasement 206 and the stator 202 may bedescribed as a closed channel relationship in which the encasement 206is arranged with the stator 202 and the plate 210 to provide a closedcoolant channel for the end windings 204. An inlet 203 and an outlet 205may be open to the closed coolant channel to deliver and remove coolant.The end windings 204 may extend through a cavity defined by the stator202, though only a portion of the end windings 204 are shown forclarity. For example, the encasement 206 may be sized to receive endwindings 204 extending therein. The rotor 208 may be sized for disposalwithin the cavity defined by the stator 202. The plate 210 may bedisposed between the stator 202 and the encasement 206. The stator 202and/or the encasement 206 may define a recess 211 to receive the plate210 therebetween. The stator 202 may define one or more apertures 207for alignment with an aperture 216 of the plate 210 to assist insecuring the plate 210 to the stator 202. For example, a bolt or otherfastener may secure the plate 210 to the stator 202 via the apertures207 and 216.

A first fastener assembly 220 may assist in securing the encasement 206to the plate 210. For example, the plate 210 may define a tab 226 andthe encasement 206 may define a key 222. The tab 226 and the key 222 maybe sized for engagement. For example, the tab 226 may define an apertureor receiving cavity to receive a portion of the key 222 such that theencasement may be secured to the plate 210. A second fastener assembly227 may also assist in securing the encasement 206 to the plate 210. Forexample, the plate 210 may define a slot 228 sized to receive anextension 230 of the encasement 206. The slot 228 and the extension 230may be arranged with one another, such as in an arrangement facilitatinga snap engagement, to assist in aligning the tab 226 and key 222 forengagement. The slot 228 may also be located on the stator 202 such thatthe aperture 216 of the plate 210 aligns with the aperture 207 of thestator 202 when the extension 230 is disposed within the slot 228.Multiple fastener assemblies 220 and 227 may be used to further assistin securing the encasement to the plate 210. A sealant may be disposedbetween one of or both of the stator 202 and the plate 210 or the plate210 and the encasement 206 to assist in sealing the closed coolantchannel. It is contemplated that another encasement, similar toencasement 206, may be secured in a similar manner to the stator 202opposite the encasement 206 to contain end windings 204 protruding outof the stator 202.

FIGS. 11A through 11C show an example of a portion of an electricmachine, referred to generally as an electric machine 300 herein. Theelectric machine 300 may include a stator 302, end windings 304, anencasement 306, a rotor 308, and a plate 310. In this example, arelationship between the encasement 306 and the stator 302 may bedescribed as a closed channel relationship in which the encasement 306is arranged with the stator 302 and the plate 310 to provide a closedcoolant channel for the end windings 304. The end windings 304 mayextend through a cavity defined by the stator. The encasement 306 may besized to receive end windings 304 extending therein. An inlet 303 and anoutlet 305 may be open to the closed coolant channel to deliver andremove coolant. The rotor 308 may be sized for disposal within thecavity defined by the stator 302. The plate 310 may be disposed betweenthe stator 302 and the encasement 306. The stator 302 and/or theencasement 306 may define a recess to receive the plate 310therebetween. The stator 302 may define one or more apertures 307 foralignment with an aperture 319 of the plate 310 to assist in securingthe plate 310 to the stator 302. For example, a bolt or other fastenermay secure the plate 310 to the stator 302 via the apertures 307 and319.

The encasement 306 is shown separated from the plate 310 in FIGS. 11Athrough 11C to assist in showing a slot 316 defined by the plate 310 anda tab 318 defined by the encasement 306. The slot 316 may be sized tohave a larger opening at one end relative to the other end. This sizedifference may assist in securing the encasement 306 to the plate 310.For example, the tab 318 may be inserted into the larger opening of theslot 316 and then the encasement 306 may be rotated such that the tab318 slides into the other end of the slot 316. An arrangement of theslot 316 and the tab 318 may be such that the encasement 306 is securedto the plate 310 when the tab 318 is engaged with the side surfaces ofthe slot 316. It is contemplated that another encasement, similar toencasement 306, may be secured in a similar manner to the stator 302opposite the encasement 306 to contain end windings 304 protruding outof the stator 302.

FIGS. 12 through 15 show an example of an operation to form anencasement for end windings of an electric machine. FIG. 12 shows aschematic of a portion of an electric machine which may include a stator402, end windings 404, an encasement 406, an inlet 410, and an outlet412. The encasement 406 may be formed via a mold process to create aclosed coolant channel for the end windings 404. For example, adissolvable base mold 420 may be applied to the end windings 404 asshown in FIG. 13. The base mold 420 may be made from, for example, wax,sugar, or salt. The base mold 420 may also be made of a thermallyconductive material to assist in removing heat from the end windings404. The end windings 404 may be immersed in a bath of the base mold 420and then removed such that the base mold 420 may solidify. Multipleimmersions may be executed to achieve a desired thickness of the basemold 420. Placeholders for the inlet 410 and outlet 412 may be insertedwithin base mold 420. While FIGS. 13 through 15 show a space between thebase mold 420 and the stator 402, it is contemplated that the base mold420 may be formed such that the base mold 420 contacts the stator 402.It is also contemplated that the base mold 420 may have an L-shapeinstead of surrounding the end windings 404 as shown in FIG. 13.

The base mold 420 and end windings 404 may then be immersed in a bath ofepoxy and then removed such that an over mold 422 may be formed as shownin FIG. 14. Multiple immersions may be executed to achieve a desiredthickness of the over mold 422. The base mold 420 may then be removed tocreate a cavity. For example, removing the base mold 420 provides acavity 430 defined between the end windings 404 and the over mold 422. Aliquid may be applied to the base mold 420 via the inlet 410 to dissolvethe over mold 422. The liquid may have characteristics which react withthe desired material of the over mold 422 to dissolve the same. Inanother example, the base mold 420 may be made of wax. In this example,heat may be applied proximate the wax to melt the same to define thecavity 430. As such, the encasement 406 may be formed to define a closedcoolant channel about the end windings 404 for coolant to flow throughand assist in managing thermal conditions of the end windings 404.

The words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments may becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics may becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes mayinclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, embodimentsdescribed as less desirable than other embodiments or prior artimplementations with respect to one or more characteristics are notoutside the scope of the disclosure and may be desirable for particularapplications.

What is claimed is:
 1. An electric machine housing cover comprising: aninner sidewall; and an outer sidewall spaced from the inner sidewall todefine a coolant channel therebetween, wherein the sidewalls are definedby an interior cover surface, wherein the coolant channel receivesstator end windings when the cover is secured to the housing, andwherein the interior cover surface defines a meandering trough betweenthe sidewalls to form a predetermined coolant path relative to endwinding locations.
 2. The cover of claim 1, wherein the interior coversurface defines features between the sidewalls to promote turbulence ofcoolant flowing through the coolant channel, and wherein the featuresare one of a plurality of individual extrusions scattered about thecoolant channel, concentric circular extrusions about a hub of thecoolant channel, or post extrusions spaced apart from one another alongthe inner sidewall or outer sidewall.
 3. The cover of claim 1, whereinthe cover defines an inlet and an outlet open to the coolant channel. 4.The cover of claim 1 further comprising a stator, wherein the stator andthe outer sidewall are sized such that the coolant channel is sealedwhen the cover is secured to the electric machine housing.
 5. The coverof claim 1, wherein the cover further defines one or more fins on anexterior surface proximate the coolant channel to operate as a heatsink.
 6. A housing of an electrified vehicle electric machinecomprising: a cover defining an interior surface and an exteriorsurface; an inner sidewall defined by the interior surface and having acircular shape; and an outer sidewall defined by the interior surfaceand spaced apart from the inner sidewall to define a coolant channeltherebetween, wherein the interior surface is arranged with the housingsuch that the coolant channel receives end windings of a stator of theelectric machine when the cover is secured to the housing, and whereinthe outer sidewall is spaced from an edge of the cover such that a rotorof the electric machine at least partially extends in between thesidewalls.
 7. The housing of claim 6, wherein the interior surfacefurther defines a meandering trough between the inner sidewall and outersidewall for coolant to flow therethrough.
 8. The housing of claim 6,wherein the outer sidewall further defines an inlet and an outlet opento the coolant channel.
 9. The housing of claim 6, wherein the innersidewall defines a cavity sized for a rotor of the electric machine toat least partially extend therethrough.
 10. The housing of claim 6further comprising a sealant disposed between the sidewalls and thestator.
 11. The housing of claim 6, wherein the stator further defines abracket extending from a face of the stator sized to receive a keydefined by the outer sidewall to secure the outer sidewall to thestator.
 12. The housing of claim 6, wherein the stator defines a slotsized to receive a tab defined by the outer sidewall to secure the outersidewall to the stator.
 13. The housing of claim 6 further comprising anO-ring plate sized for disposal between the sidewalls and the stator.14. The housing of claim 6, further comprising one or more finsextending from an exterior cover surface and located proximate thecoolant channel.
 15. The housing of claim 14, wherein the one or morefins are adjacent one of an inlet or outlet defined by the outersidewall.
 16. A method to form an encasement about end windings of anelectric machine comprising: immersing the end windings in a moldmaterial bath and then removing the end windings for the mold materialto solidify and define a base mold upon the end windings; positioninginlet and outlet placeholders extending in and out of the base mold;immersing the base mold in an epoxy bath and then removing the base moldfor the epoxy to solidify and define an over mold; and dissolving thebase mold via a liquid applied to the base mold such that a cavity isdefined between the end windings and the over mold.